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Dauga C,
( 2002 ) Evolution of the gyrB gene and the molecular phylogeny of Enterobacteriaceae: a model molecule for molecular systematic studies. PMID : 11931166 : DOI : 10.1099/00207713-52-2-531 Abstract >>
Phylogenetic trees showing the evolutionary relatedness of Enterobacteriaceae based upon gyrB and 16S rRNA genes were compared. Congruence among trees of these molecules indicates that the genomes of these species are not completely mosaic and that molecular systematic studies can be carried out. Phylogenetic trees based on gyrB sequences appeared to be more reliable at determining relationships among Serratia species than trees based on 16S rRNA gene sequences. gyrB sequences from Serratia species formed a monophyletic group validated by significant bootstrap values. Serratia fonticola had the most deeply branching gyrB sequence in the Serratia monophyletic group, which was consistent with its atypical phenotypic characteristics. Klebsiella and Enterobacter genera seemed to be polyphyletic, but the branching patterns of gyrB and 16S rRNA gene trees were not congruent. Enterobacter aerogenes was grouped with Klebsiella pneumoniae on the gyrB phylogenetic tree, which supports that this species could be transferred to the Klebsiella genus. Unfortunately, 16S rRNA and gyrB phylogenetic trees gave conflicting evolutionary relationships for Citrobacter freundii because of its unusual gyrB evolutionary process. gyrB lateral gene transfer was suspected for Hafnia alvei. Saturation of gyrB genes was observed by the pairwise comparison of Proteus spp., Providencia alcalifaciens and Morganella morganii sequences. Depending on their level of variability, 16S rRNA gene sequences were useful for describing phylogenetic relationships between distantly related Enterobacteriaceae, whereas gyrB sequence comparison was useful for inferring intra- and some intergeneric relationships.
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Hurst MR,
Glare TR,
Jackson TA,
Ronson CW,
( 2000 ) Plasmid-located pathogenicity determinants of Serratia entomophila, the causal agent of amber disease of grass grub, show similarity to the insecticidal toxins of Photorhabdus luminescens. PMID : 10960097 : DOI : 10.1128/jb.182.18.5127-5138.2000 PMC : PMC94661 Abstract >>
Serratia entomophila and Serratia proteamaculans cause amber disease in the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae), an important pasture pest in New Zealand. Larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. A 115-kb plasmid, pADAP, identified in S. entomophila is required for disease causation and, when introduced into Escherichia coli, enables that organism to cause amber disease. A 23-kb fragment of pADAP that conferred disease-causing ability on E. coli and a pADAP-cured strain of S. entomophila was isolated. Using insertion mutagenesis, the pathogenicity determinants were mapped to a 17-kb region of the clone. Sequence analysis of the 17-kb region showed that the predicted products of three of the open reading frames (sepA, sepB, and sepC) showed significant sequence similarity to components of the insecticidal toxin produced by the bacterium Photorhabdus luminescens. Transposon insertions in sepA, sepB, or sepC completely abolished both gut clearance and cessation of feeding on the 23-kb clone; when recombined back into pADAP, they abolished gut clearance but not cessation of feeding. These results suggest that SepA, SepB, and SepC together are sufficient for amber disease causation by S. entomophila and that another locus also able to exert a cessation-of-feeding effect is encoded elsewhere on pADAP.
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Pham HN,
Ohkusu K,
Mishima N,
Noda M,
Monir Shah M,
Sun X,
Hayashi M,
Ezaki T,
( 2007 ) Phylogeny and species identification of the family Enterobacteriaceae based on dnaJ sequences. PMID : 17368802 : DOI : 10.1016/j.diagmicrobio.2006.12.019 Abstract >>
Phylogenetic relations within the family Enterobacteriaceae were analyzed using partial dnaJ sequences of 165 strains belonging to 93 species from 27 enterobacterial genera. The dnaJ phylogeny was in relative agreement with that constructed by 16S rDNA sequences, but more monophyletic groups were obtained from the dnaJ tree than from the 16S rDNA tree. The degree of divergence of the dnaJ gene was approximately 6 times greater than that of 16S rDNA. Also, the dnaJ gene showed the most discriminatory power in comparison with tuf and atpD genes, facilitating clear differentiation of any 2 enterobacterial species by dnaJ sequence analysis. The application of dnaJ sequences to the identification was confirmed by assigning 72 clinical isolates to the correct enterobacterial species. Our data indicate that analysis of the dnaJ gene sequences can be used as a powerful marker for phylogenetic study and identification at the species level of the family Enterobacteriaceae.
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Hurst MR,
Glare TR,
Jackson TA,
( 2004 ) Cloning Serratia entomophila antifeeding genes--a putative defective prophage active against the grass grub Costelytra zealandica. PMID : 15262948 : DOI : 10.1128/JB.186.15.5116-5128.2004 PMC : PMC451664 Abstract >>
Serratia entomophila and Serratia proteamaculans (Enterobacteriaceae) cause amber disease in the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae), an important pasture pest in New Zealand. Larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. A 155-kb plasmid, pADAP, carries the genes sepA, sepB, and sepC, which are essential for production of amber disease symptoms. Transposon insertions in any of the sep genes in pADAP abolish gut clearance but not cessation of feeding, indicating the presence of an antifeeding gene(s) elsewhere on pADAP. Based on deletion analysis of pADAP and subsequent sequence data, a 47-kb clone was constructed, which when placed in either an Escherichia coli or a Serratia background exerted strong antifeeding activity and often led to rapid death of the infected grass grub larvae. Sequence data show that the antifeeding component is part of a large gene cluster that may form a defective prophage and that six potential members of this prophage are present in Photorhabdus luminescens subsp. laumondii TTO1, a species which also has sep gene homologues.
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Hurst MR,
O'Callaghan M,
Glare TR,
( 2003 ) Peripheral sequences of the Serratia entomophila pADAP virulence-associated region. PMID : 14597010 : Abstract >>
Some strains of the Enterobacteriaceae Serratia entomophila and Serratia proteamaculans cause amber disease in the grass grub, Costelytra zealandica (Coleoptera: Scarabaeidae), an important pasture pest in New Zealand. The genes responsible for this disease reside on a large, 155-kb plasmid designated amber disease-associated plasmid (pADAP). Herein, we report the DNA sequencing of approximately 50 kb upstream and 10 kb downstream of the virulence-encoding region. Based on similarity with proteins in the current databases, and potential ribosome-binding sites, 63 potential ORFs were determined. Eleven of these ORFs belong to a type IV pilus cluster (pilL-V) and a further eight have similarities to the translated products of the plasmid transfer traH-N genes of the plasmid R64. In addition, a degenerate 785-nt direct repeat flanks a 44.7-kb region with the potential to encode three Bacillus subtilis Yee-type proteins, a fimbrial gene cluster, the sep virulence-associated genes and several remnant IS elements.
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( 1996 ) The amb2 locus from Serratia entomophila confers anti-feeding effect on larvae of Costelytra zealandica (Coleoptera: Scarabaeidae). PMID : 8654995 : DOI : 10.1016/0378-1119(96)00055-8 Abstract >>
Serratia entomophila (Se) causes amber disease in the soil-dwelling pest, Costelytra zealandica (Cz). The disease presents two main signs: anti-feeding effect (AFE) and development of amber coloration (AC). To identify the genetic loci involved in pathogenicity, non-pathogenic (Path-) Se mutants were created by transposon (TnphoA) mutagenesis [Upadhyaya et al., J. Bacteriol. 174 (1992) 1020-1028]. The mutant UC24 lost the ability to produce amber disease signs and it was shown to contain a single TnphoA insertion. The TnphoA insertion site was mapped in a 5.3-kb DNA fragment, which was named amb2 locus. Cosmids containing amb2 fully restored AFE and partially restored AC in UC24. Escherichia coli (Ec) HB101 bearing the amb2 locus was able to cause AFE in a multiple-dose bioassay. SDS-PAGE analysis of the amb2 gene products produced in minicells showed the synthesis of two proteins of 16 and 19.5 kDa, named AnfA and AnfB. The genes encoding these proteins were mapped by deletion analysis. Pathogenicity tests with insect larvae fed with bacteria carrying the anfA and anfB gene regions separately showed that both regions are essential for AFE. It is proposed that the AnfA and AnfB proteins are virulence factors (toxin-like proteins) causing AFE in Cz.
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( 2013 ) Serratia entomophila bet gene induction and the impact of glycine betaine accumulation on desiccation tolerance. PMID : 23110363 : DOI : 10.1111/jam.12052 Abstract >>
The genes involved in choline transport and oxidation to glycine betaine in the biopesticidal bacterium Serratia entomophila were characterized, and the potential of osmoprotectants, coupled with increased NaCl concentrations, to improve the desiccation tolerance of this species was investigated. Serratia entomophila carries sequences similar to the Escherichia coli betTIBA genes encoding a choline transporter and dehydrogenase, a betaine aldehyde dehydrogenase and a regulatory protein. Disruption of betA abolished the ability of Ser. entomophila to utilize choline as a carbon source. Quantitative reverse-transcriptase PCR analysis revealed that betA transcription was reduced compared to that of the upstream genes in the operon, and that NaCl and choline induced bet gene expression. Glycine betaine and choline increased the NaCl tolerance of Ser. entomophila, and osmotically preconditioned cultures survived better than control cultures following desiccation and immediately after application to agricultural soil. Addition of glycine betaine and NaCl to growth medium can greatly enhance the desiccation survival of Ser. entomophila, and its initial survival in soil. Serratia entomophila is sensitive to desiccation and does not persist under low soil moisture conditions. Techniques described here for enhancing the desiccation survival of Ser. entomophila can be used to improve formulations of this bacterium, and allow its application under a wider range of environmental conditions.
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